In more detail, my hypothesis follows:

1) Assumptions

1a) The photograph is genuine, and the subjects in the image do not involve any sort of illusion, such as period costumes, props, or scenery.

1b) The star of the picture is a bony fish.

1c) The fish lies mostly on its right side, though the head may be at least partly propped up with another object, such as the one fellow’s boot (“OK, push a little to the right; now a little forward.”)

1d) No fins of any significant size have been removed from the fish, either before or after its meeting with the men in the photo.

1e) No other organs of any significance have been removed from the fish, or if they have, then their removal has not significantly altered its overall shape or characters.

1f) The “upward bend” of the “mouth” is actually the gill cover opening, and only the “front 1/4″ of the “mouth” is the mouth. The dark line connecting these two features is the injury created when the bill hook used to pull the fish tore through its “cheek” from gill cover to inner edge of mouth.

2) Arguments in favor of “relative of electric eel” hypothesis

2a) The overall shape of the head and body match reasonably well, except that the fish in the picture is more “stout” and less elongated.

2b) Tiny pectoral fins like those of an electric eel might not be visible, especially if there is an injury or bit of shrubbery obscuring that part of the fish.

2c) The long “ventral fin” (if that’s the proper term) of a creature like the electric eel could be folded under its body, thus giving the fish the appearance of being completely finless.

2d) Electric eels are native to swamps and marshes of South America, so it is not beyond the bounds of reason to suggest that a larger relative could exist in Nicaragua.

2d) The size of the fish, while impressive for a presumed fresh-water creature, would not break any kind of record.

2e) The expressions of the men might not arise from amusement, as suggested by one person, but from discomfort and mistrust, particularly if one or more people were injured or killed by the creature’s electric shocks.

3) Some potential problems with the “relative of electric eel” hypothesis

3a) “While the length of our subject is not excessive for an electric eel, its depth of body is substantially greater, yielding a different aspect ratio and much greater mass, perhaps 20-50 times that of an electric eel.” This problem essentially excludes the electric eel per se, but I know of no biological reason that would prevent a related genus or species from growing to this size. The “tail” of an electric eel contains mostly the specialized muscles used to create electric potentials, but a thicker creature may not need to create *larger* shocks to stun its prey than the electric eel does, and so might reasonably get by with a proportionately smaller electric apparatus.

3b) “The barred coloring of our subject resembles that of open-water fish more so than that of electric eels, which tend toward simpler top/bottom countershading.” However, a different ecological niche would require different camouflage.

3c) “Electric fish of such large size certainly would have attracted the attention of scientists by now.” To some extent, this argument may be applied to any cryptid, and is usually countered by suggesting that the creatures are rare or elusive, or that scientists from industrialized countries have ignored local knowledge of such creatures. In particular, if these fish were native to a shallow swamp or marsh that was later drained to make way for agriculture, used as a landfill, or contaminated with mine tailings, the poor creatures easily could have gone extinct in anonymity.

The “mouth” which some have alluded to isn’t a mouth at all. I would guess it is a combined blood streak and injury from being gaff-hooked, probably by the same instrument that is in the foreground. There seems to be a good candidate for a dorsal fin under the gaff-pole.

Seems to be a trophy picture of a dead shark, but in an unusual pose. I’d surmise that with such a nasty looking and big fish, the men weren’t keen on handling it to pose it more favorably. Thus they took a picture of it as best they could, probably with the fish lying in the same position it was dragged to land in.

After a million hits to the various threads, we’re still debating what *kind* of animal this is – bony fish, shark, mammal, etc.

I spent a bit of time enlarging and enhancing the tail section of this animal, and overlaying it with some lines to show what I’m seeing.

You can see the results at my website, Where Light Meets Dark.

As noted above in the commentary here, I conclude from the tail that it’s a bony fish; but at the same time, if I were looking at the head end only, I’d say it was a shark.

I’m basically of the opinion that the right side of the creature is where it was severed from the rest of the body. From what I can tell we are only looking at part (only the head and neck) of a larger animal.

Re: Styrofoam. Remember this is allegedly around the turn of the century and a lot of the things that could be used to hoax something like this now were not in existence then.

Secondly – look at the tail. You can see the caudal peduncle – the junction between the caudal (or tail) fin itself, and the body. It is laterally compressed. In other words, the body is definately on its side and the tail matches a fish, not a whale.

Someone wrote “we will never know”. To the contrary – if we can identify the people, then perhaps locate family, friends or written evidence such as a journal, diary or letter, then we may well find out.

Regarding the Philippines and Nicaragua – it simply strikes me as odd that when you search for the exact same text, you get only a handful of matches, one of which is claimed to be from a series of 40 taken in Nicaragua which often showed the marines in the photo.

Postcards are collectable. People document antique postcards. I still think the Nicaraguan connection is the strongest one we have.

If there are any military researchers amongst us, they should start finding the lists of names of people who went to San Juan Del Sur.

Chris.